Relay circuit



July27, 1937. A, 1 BUSCH 2,088,318

RELAY CIRCUIT l Filed Maren 11, 19:56

la ,lig/f@ .lilik/f I' /Nl/EA/TOR A. J. BUSCH A T TURA/Er Cil Patented July 27, 1937 NTED STATES PATENT orma RELAY CIRCUIT Application March 11, 1936, Serial No. 68,240

6 Claims.

This invention relates to telephone systems and has for its object to increase the reliability of such systems.

In the cross-bar system disclosed in the application of W. W. Carpenter Serial No. 681,102, filed July 19, 1933, rst choice is given to groups of equipment, senders for example, in which two or more are idle. In that application a marginal relay arrangement is employed for identifying such groups, requiring careful adjustment of the relay and therefore continuous attention.

In accordance with the present invention, an

arrangement is provided for identifying groups.

containing at least two idle circuits by means of a set of relays, one for each circuit, which operates when the circuit is busy. An indicating circuit is provided which extends in parallel to the back contacts of all of these relays and this circuit is completed only if two relays have their back contacts closed. Each relay is equipped with a pair of connected armatures having two back contacts and one front contact and the indicating circuit extends over the two back contacts of two relays and may include one or more front contacts of intermediate relays.

This arrangement is disclosed in connection with a complete cross-bar system in the application of W. W. Carpenter Serial No. 68,262, filed March 11, 1936.

The invention is illustrated in the accompanying drawing which shows four of a set of ten relays. Relays |00 to |09 are individual respectively to the ten circuits of a group No. 0 to No. 9 connected thereto over conductors ||0 to H9, When a circuit, for example circuit No. 0, is busy, relay |30 of that circuit is operated and ground is connected to the corresponding conductor ||0 and the individual relay |00 operated. The condition of the group of circuits is indicated to the test equipment (not shown) over conductor |20. This conductor extends in parallel to the outer back contacts of all of the relays |00 to |09. When a relay, for example relay |00, is unoperated, indicating that the corresponding equipment No. 0 is idle, the conducto-r is connected over its outer armature to the inner contact of the next relay in the chain, relay |0|. If relay |0| is also unoperatcd, indicating the existence of a second idle circuit, this inner contact is closed to battery, thereby connecting battery to conductor |20 as an indication that this group of circuits includes two idle ones and is ready for preferred use.

Ifthe No. 1 circuit is busy so that relay I0| is operated, its inner contact is connected to the inner contact of the next relay of the chain, where the circuit may extend to battery or to the inner contact oi the following relay.

Each relay in operating disconnects its outer k armature from conductor |20, opening one of the group indicating circuits and at its inner armature transfers another group circuit from battery to a subsequent relay. Each relay in operating, withdraws from the two chain circuits which are controlled over its contacts.

If only relay |0|, for example, were idle, the circuits over the back contacts of relay |00, the relays intermediate relays 10| and |08 and relays |08 and |09 would all be open, the circuit prepared at the outer back contact of relay |0| would be open at the inner back contacts of the intermediate relays and relays |08 and |09.

On the other hand, if none of the relays |00 to- |09 were operated, conductor |20 would receive battery over nine circuits, including one over the outer back contact of relay |00 and the inner back contact of relay |0l, one over the outer back contact of relay |08 and the inner back contact of relay |09 and seven circuits including contacts of relays not shown.

If relays |00 and |09 were the only relays not operated, conductor |20 would receive battery over the outer back contact of relay |00, the front contacts of relay IUI, the intermediate relays and relay |08 and the inner back contact of relay |09.

What is claimed is:

l. In a telephone system, means for indicating when more than a given number of circuits are idle comprising a relay for each of said circuits, means in each circuit for operating the corresponding relay when said circuit is busy and a chain circuit completed over the back contacts of said given number of relays.

2. In a telephone system, means for indicating when more than a given number of circuits are idle comprising a relay for each of said circuits, means in each circuit for operating the corresponding relay and an indicating circuit extending in parallel to the back contacts of all of said relays, said circuit being completed over the back contact of any relay only if the back contact of a succeeding relay is also closed.

3. In a telephone system, a group of circuits, means for marking said circuits-as busy or idle, a relay for each of said circuits, each relay having at least two back contacts and one front contact, and a circuit for indicating the availability of said groups of circuits, said circuit extending in parallel to one back cont-act of each of said relays `and completed over one of said back contacts only if the second back contact of a succeeding relay is also closed.

4. In a telephone system, a group of circuits, means for marking s-aid circuits as busy or idle, a relay for each of said circuits, each relay having at least two back contacts and one front Contact, and a circuit for indicatingthe availability of said group of circuits, said circuit extending in parallel to one backcontact of each of said relays and completed over the front contact of operated relays and the other back contact of a second unoperated relay.

5. A chain of relays for indicating the availability of a group of circuits, each of said relays being oper-ated when the corresponding circuit is unavailable, including two connected armatures on each relay having two back contacts and oneV front contact, and an indicating circuit closed over the two back contacts of two of said relays.

6. A chain of relays for indicating the availability of a group of circuits, each of said relays being operated when the corresponding circuit is unavailable, including two connected armatures on each relay having two back contacts and one front contact and an indicating circuit closed over the two back contacts of two of said relays, said circuit including the front contacts of operated relays intermediate said two relays.

ALOYSIUS J. BUSCH. 

